During chip manufacturing, substrates experience non-uniform localized distortions which, if uncorrected, cause misalignments of lithography patterns between layers. The registration may be corrected for certain types of distortions in that the pattern can be optically matched during the lithography print. For other types of distortions, however, correction is not possible and a yield loss results. Furthermore, as feature sizes continue to shrink, the tolerance to distortions decreases and the number of uncorrectable distortions increases.
Distortions have previously been corrected for via the local implantation of controlled amounts of ions into the hardmask to create local strains. The local strains compensate the previously existing ones. However, contamination of the underlying layers by the chosen ion is possible.
Other attempts to correct for distortions involve variable local surface annealing of the hardmask to create local strains which compensate the previously existing ones. One the other hand, however, partial relaxation occurs as the surface of the hardmask is removed during subsequent processing.
Therefore, what is needed in the art is a method and apparatus for treating the backside of a substrate.